1. Field of the Invention
The present invention relates to a laminated structure for a fluid, which is formed with fluid passages therein. More specifically, the present invention concerns a laminated structure for a fluid, in which an intermediate member is interposed between metallic block members to form fluid passages therein, wherein the elastic constant of the intermediate member is greater than that of the metallic block members, and further wherein the members are each joined together by diffusion bonding or welding.
2. Description of the Related Art
For the purpose of delivering a pressure fluid to a desired location and driving a fluid-operated device, a fluid passage is arranged between a pressure fluid supply source (e.g., a negative pressure supply source) and the fluid-operated device. These types of fluid passages are provided by drilling holes into metallic or resin blocks, and forming grooves therein by photoetching, or in certain cases, by pressing. In recent years, in accordance with space reduction and the arrangement conditions of various devices, structures have been adopted in which fluid passages are developed in three dimensions inside of a block body, and along with such requirements, a structure is adopted in which a plurality of blocks making up the block body are stacked or laminated on each other.
In this type of laminated structure for a fluid, various methods have been adopted for joining the plurality of blocks, which are stacked and laminated together.
For example, methods are known in which a powder of magnesium or the like is supplied to bonding surfaces of a plurality of aluminum alloy members, and diffusion bonding is carried out thereon (see, Japanese Laid-Open Patent Publication Nos. 2001-262331 and 08-033990, and N. Matsumoto et al., “Electric-Joining of 5052 and 6063A1 Alloys,” 2006 Japan Institute of Metals, Lecture Outline Series (139th Meeting), Japan Institute of Metals, Sep. 16, 2006), and in which a plating layer is formed on the bonding surface of a joining base material that is diffusion bonded with another block member (see, Japanese Laid-Open Patent Publication No. 06-218559). Further, it is known to form a silver layer at the joining surface between an aluminum member and a copper member, for joining both of the members (see, Japanese Laid-Open Patent Publication No. 2005-052885).
However, with the technical concepts disclosed in the above references, when such members are joined with other members in a state in which fluid flow passages are formed therein, there are cases in which such flow passages become deformed by the other members. With such deformed flow passages, for example, fluid resistance is changed, and it becomes difficult to drive and control fluid pressure devices at a desired pressure (e.g., at a given vacuum or negative pressure). In addition, when the members are formed of synthetic resins, the strength thereof is inferior, and moreover, timewise changes over a period of years occur easily, together with the possibility that the functions thereof can vary, depending on environmental conditions.